1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * nvs.c - Routines for saving and restoring ACPI NVS memory region
4 *
5 * Copyright (C) 2008-2011 Rafael J. Wysocki <rjw@sisk.pl>, Novell Inc.
6 */
7
8#define pr_fmt(fmt) "ACPI: PM: " fmt
9
10#include <linux/io.h>
11#include <linux/kernel.h>
12#include <linux/list.h>
13#include <linux/mm.h>
14#include <linux/slab.h>
15#include <linux/acpi.h>
16
17#include "internal.h"
18
19/* ACPI NVS regions, APEI may use it */
20
21struct nvs_region {
22 __u64 phys_start;
23 __u64 size;
24 struct list_head node;
25};
26
27static LIST_HEAD(nvs_region_list);
28
29#ifdef CONFIG_ACPI_SLEEP
30static int suspend_nvs_register(unsigned long start, unsigned long size);
31#else
32static inline int suspend_nvs_register(unsigned long a, unsigned long b)
33{
34 return 0;
35}
36#endif
37
38int acpi_nvs_register(__u64 start, __u64 size)
39{
40 struct nvs_region *region;
41
42 region = kmalloc(sizeof(*region), GFP_KERNEL);
43 if (!region)
44 return -ENOMEM;
45 region->phys_start = start;
46 region->size = size;
47 list_add_tail(new: &region->node, head: &nvs_region_list);
48
49 return suspend_nvs_register(start, size);
50}
51
52int acpi_nvs_for_each_region(int (*func)(__u64 start, __u64 size, void *data),
53 void *data)
54{
55 int rc;
56 struct nvs_region *region;
57
58 list_for_each_entry(region, &nvs_region_list, node) {
59 rc = func(region->phys_start, region->size, data);
60 if (rc)
61 return rc;
62 }
63
64 return 0;
65}
66
67
68#ifdef CONFIG_ACPI_SLEEP
69/*
70 * Platforms, like ACPI, may want us to save some memory used by them during
71 * suspend and to restore the contents of this memory during the subsequent
72 * resume. The code below implements a mechanism allowing us to do that.
73 */
74
75struct nvs_page {
76 unsigned long phys_start;
77 unsigned int size;
78 void *kaddr;
79 void *data;
80 bool unmap;
81 struct list_head node;
82};
83
84static LIST_HEAD(nvs_list);
85
86/**
87 * suspend_nvs_register - register platform NVS memory region to save
88 * @start: Physical address of the region.
89 * @size: Size of the region.
90 *
91 * The NVS region need not be page-aligned (both ends) and we arrange
92 * things so that the data from page-aligned addresses in this region will
93 * be copied into separate RAM pages.
94 */
95static int suspend_nvs_register(unsigned long start, unsigned long size)
96{
97 struct nvs_page *entry, *next;
98
99 pr_info("Registering ACPI NVS region [mem %#010lx-%#010lx] (%ld bytes)\n",
100 start, start + size - 1, size);
101
102 while (size > 0) {
103 unsigned int nr_bytes;
104
105 entry = kzalloc(sizeof(struct nvs_page), GFP_KERNEL);
106 if (!entry)
107 goto Error;
108
109 list_add_tail(new: &entry->node, head: &nvs_list);
110 entry->phys_start = start;
111 nr_bytes = PAGE_SIZE - (start & ~PAGE_MASK);
112 entry->size = (size < nr_bytes) ? size : nr_bytes;
113
114 start += entry->size;
115 size -= entry->size;
116 }
117 return 0;
118
119 Error:
120 list_for_each_entry_safe(entry, next, &nvs_list, node) {
121 list_del(entry: &entry->node);
122 kfree(objp: entry);
123 }
124 return -ENOMEM;
125}
126
127/**
128 * suspend_nvs_free - free data pages allocated for saving NVS regions
129 */
130void suspend_nvs_free(void)
131{
132 struct nvs_page *entry;
133
134 list_for_each_entry(entry, &nvs_list, node)
135 if (entry->data) {
136 free_page((unsigned long)entry->data);
137 entry->data = NULL;
138 if (entry->kaddr) {
139 if (entry->unmap) {
140 iounmap(addr: entry->kaddr);
141 entry->unmap = false;
142 } else {
143 acpi_os_unmap_iomem(virt: entry->kaddr,
144 size: entry->size);
145 }
146 entry->kaddr = NULL;
147 }
148 }
149}
150
151/**
152 * suspend_nvs_alloc - allocate memory necessary for saving NVS regions
153 */
154int suspend_nvs_alloc(void)
155{
156 struct nvs_page *entry;
157
158 list_for_each_entry(entry, &nvs_list, node) {
159 entry->data = (void *)__get_free_page(GFP_KERNEL);
160 if (!entry->data) {
161 suspend_nvs_free();
162 return -ENOMEM;
163 }
164 }
165 return 0;
166}
167
168/**
169 * suspend_nvs_save - save NVS memory regions
170 */
171int suspend_nvs_save(void)
172{
173 struct nvs_page *entry;
174
175 pr_info("Saving platform NVS memory\n");
176
177 list_for_each_entry(entry, &nvs_list, node)
178 if (entry->data) {
179 unsigned long phys = entry->phys_start;
180 unsigned int size = entry->size;
181
182 entry->kaddr = acpi_os_get_iomem(phys, size);
183 if (!entry->kaddr) {
184 entry->kaddr = acpi_os_ioremap(phys, size);
185 entry->unmap = !!entry->kaddr;
186 }
187 if (!entry->kaddr) {
188 suspend_nvs_free();
189 return -ENOMEM;
190 }
191 memcpy(to: entry->data, from: entry->kaddr, len: entry->size);
192 }
193
194 return 0;
195}
196
197/**
198 * suspend_nvs_restore - restore NVS memory regions
199 *
200 * This function is going to be called with interrupts disabled, so it
201 * cannot iounmap the virtual addresses used to access the NVS region.
202 */
203void suspend_nvs_restore(void)
204{
205 struct nvs_page *entry;
206
207 pr_info("Restoring platform NVS memory\n");
208
209 list_for_each_entry(entry, &nvs_list, node)
210 if (entry->data)
211 memcpy(to: entry->kaddr, from: entry->data, len: entry->size);
212}
213#endif
214